Vascular smooth muscle cells (SMCs) undergo morphological and phenotypic changes when cultured in vitro. To investigate whether SMC morphology regulates SMC functions, bovine aortic SMCs were grown on micropatterned collagen strips (50-, 30-, and 20-mum wide). The cell shape index and proliferation rate of SMCs on 30- and 20-mum strips were significantly lower than those on non-patterned collagen (control), and the spreading area was decreased only for cells patterned on the 20-mum strips, suggesting that SMC proliferation is dependent on cell shape index. The formation of actin stress fibers and the expression of alpha-actin were decreased in SMCs on the 20- and 30-mum collagen strips. SMCs cultured on micropatterned biomaterial poly-(D,L-lactide-co-glycolide) (PLGA) with 30-mum wide grooves also showed lower proliferation rate and less stress fibers than SMCs on non-patterned PLGA. Our findings suggest that micropatterned matrix proteins and topography can be used to control SMC morphology and that elongated cell morphology decreases SMC proliferation but is not sufficient to promote contractile phenotype. (C) 2003 Elsevier Inc. All rights reserved.